Polyester polyols produced from dicarboxylic acid anhydrides, polyols and polyepoxides are known. In U.S. Pat. No. 4,403,093, such polyester polyols are produced by first reacting a 1,2-dicarboxylic acid anhydride with a polyol under conditions sufficient to form a half-ester with substantially no polyesterification product. The resultant half-ester is then reacted with a polyepoxide under conditions sufficient to form an ungelled polyester oligomer. The resultant polyester oligomers are described as being useful as resinous binders in high solid containing compositions.
Polyester polyols produced from aromatic acids and polyoxyethylene glycols are also known and are described as being useful in the production of rigid polyurethane foams (see, e.g., U.S. Pat. No. 4,039,487 and German Auslegeschrift 1,155,908).
Finally, in the known polyurethane/urea reaction injection molding (RIM) process, a wide variety of different polyols have been suggested (see e.g., U.S. Pat. Nos. 3,726,952, 4,218,543, 4,288,564, 4,442,235, 4,519,965, 4,581,396, 4,764,540, and 4,789,688, British Patent 1,534,258. Similarly polyester polyols of various types have been suggested for use in the RIM process (see, e.g., U.S. Pat. Nos. 4,481,309, 4,590,219 and 4,595,705).